I am gonna go ahead and weigh in as a football "neutral" to this area (since I am cursed with Bengals fandom) and tell Ravens fans there is no good reason to lower expectations - go ahead and dream big. Maybe MAYBE there is another team as good as Baltimore, but I haven't seen it this year. The Ravens absolutely should be thinking Super Bowl and a trophy. Doesn't mean they will get there and get one, but there is zero reason to think they can't. They are just as good an any other elite team you could name. And, unlike almost every other team, they are absolutely built to win in any conditions. If it's a massive cold or wind or monsoon or blizzard, none of that will really negatively affect them like it will others.
As long as Jackson is upright and able to run with no pulled muscles etc, I see no reason why you all should not dream big for 2019 and for any upcoming season where he is upright and healthy for the next 5-10 years.